Obesity is a common comorbidity of type 2 diabetes. Obesity is significantly associated with an increased risk for the development of type 2 diabetes and the development of cardiovascular pathology. Although nonsurgical weight loss therapies for obesity with type 2 diabetes such as controlled diet, exercise, and medications can improve glycemic and other metabolic markers in the short term, in some patients these measures are not as effective for long-term weight loss and maintaining good glycemic control. In addition, some glucose-lowering medications (e.g., sulfonylureas, glinides, TZDs, and insulin) increase body weight. Clinical evidence suggests that surgical treatment can significantly improve glycemic control in obese patients with type 2 diabetes and may even result in “remission” of diabetes in some diabetic patients.
In 2009, the ADA formally included bariatric surgery (metabolic surgery) as a treatment for obesity with type 2 diabetes in its guidelines for the treatment of type 2 diabetes, and in 2011, the IDF issued a position statement formally recognizing metabolic surgery as a treatment for type 2 diabetes with obesity. In 2011, the CDS and the Chinese Society of Surgery also reached a consensus on metabolic surgery for the treatment of type 2 diabetes, recognizing metabolic surgery as one of the means to treat type 2 diabetes with obesity and encouraging medical-surgical cooperation in the management of patients with type 2 diabetes who undergo metabolic surgery.
I. Surgical modality and efficacy
Bariatric surgery operated through laparoscopy is the most commonly used and has the fewest complications. There are 2 main surgical modalities.
1. laparoscopic adjustable gastric banding: a restrictive procedure in which a circular band is fixed to the upper part of the gastric body to form a proximal gastric bursa and limit the outlet diameter to 12 mm, with a circular water bladder on the side of the band near the gastric wall and connected to a water injection device placed under the skin of the abdomen. Postoperatively, the internal diameter of the outlet is adjusted by filling or releasing water. Early dietary education is essential to prevent gastric bursa dilatation. The remission rate of type 2 diabetes is 60% 2 years after surgery.
2. Gastric bypass: This procedure removes the distal gastric bulk, duodenum and part of the jejunum, which both limits gastric volume and reduces nutrient absorption, and restores normal function of the intestine-islet axis. At 5-year follow-up, the remission rate of type 2 diabetes was 83%.
II. Remission criteria for surgical treatment
Postoperative treatment with lifestyle treatment only can make HbA1c≤6.5%, fasting blood glucose≤7.0mmol/L, 2h postprandial PG≤10mmol/L, without any drug treatment, and can be regarded as type 2 diabetes in remission.
Third, the indications for metabolic surgery for diabetes mellitus
1.Weight reduction/metabolic surgery can be considered in subpopulation with or without comorbidities of type 2 diabetes mellitus with BMI ≥ 35kg/m2.
2.In Asian population with BMI 30-35 kg/m2 and type 2 diabetes, weight loss/gastrointestinal metabolic surgery should be one of the treatment options when it is difficult to control blood glucose or comorbidities by lifestyle and medication, especially when there are cardiovascular risk factors.
3. In Asian population with BMI 28.0-29.9 kg/m2, if combined with type 2 diabetes and with centripetal obesity (waist circumference >85 cm for women and >90 cm for men) and at least 2 additional criteria for metabolic syndrome: triglycerides, low HDL-C level, and hypertension. Weight reduction/gastrointestinal metabolic surgery can also be considered as one of the treatment options for the above patients.
4. For adolescents with BMI ≥ 40 kg/m2 or ≥ 35 kg/m2 with severe comorbidities, and who are ≥ 15 years old, skeletally mature, and in Tanner developmental class 4 or 5, LAGB or RYGB may also be considered as a treatment option with the patient’s informed consent.
5. For type 2 diabetic patients with BMI 25.0 to 27.9 kg/m2, surgery should be performed with the patient’s informed consent and strictly according to the study protocol. However, the nature of these procedures should be considered purely as part of a pilot study approved in advance by the ethics committee only, and should not be widely promoted.
6. Patients with type 2 diabetes mellitus who are <60 years of age or in good general health with low surgical risk.
IV. Contraindications to metabolic surgery for diabetes mellitus
1, Patients with drug abuse, alcohol addiction, patients with uncontrollable mental illness and patients who lack the ability to understand the risks, benefits and expected consequences of metabolic surgery.
2. Patients with a clear diagnosis of type 1 diabetes mellitus.
3.Patients with type 2 diabetes whose pancreatic beta-cell function has significantly failed.
4.Patients with contraindications to surgical procedures.
5.Diabetic patients with BMI <28kg/m2 and whose blood glucose can be satisfactorily controlled by medication or insulin.
6.Gestational diabetes and other special types of diabetes are temporarily excluded from the scope of surgical treatment.
V. Risks of metabolic surgery
Surgical treatment of obesity with type 2 diabetes also has certain short-term and long-term risks, and the long-term effectiveness and safety of this treatment method, especially in our population, has yet to be evaluated. Several meta-analyses have shown that the mortality rate after RYGB is 0.3% to 0.5% at 30 days and 0.35% at 90 days, while the mortality rate for LAGB is 0.1%. Deep vein thrombosis and pulmonary embolism are important causes of surgically induced mortality. Postoperative complications also include bleeding, anastomotic fistula, gastrointestinal obstruction, and ulcers. Long-term complications include nutritional deficiency, cholelithiasis, and internal hernia formation.
It is recommended that the competent health administrative authorities establish a qualification admission system for this type of surgery to ensure the effectiveness and safety of the procedure. Randomized controlled studies of surgical treatment and drug treatment should be conducted in China, especially prospective studies with complications as endpoints.
VI. Management of metabolic surgery
The management of metabolic surgery should be done by the cooperation between endocrinologists and surgeons.
Preoperative screening and evaluation: Physicians with expertise in endocrinology should screen diabetic patients with poor results of medical treatment and perform preoperative evaluation of patients with indications for metabolic surgery, and recommend these patients to comprehensive medical units with qualifications for metabolic surgery.
2. Metabolic surgery treatment: The surgical treatment of type 2 diabetic patients may involve several different clinical disciplines in the treatment process and perioperative management due to the special condition of the patients, so it is recommended that the surgery should be carried out in a comprehensive medical unit of secondary and higher level. The surgeon should be a gastrointestinal surgeon with intermediate or higher title and a long-term practice in general surgery, and he/she should understand the treatment principles and operation guidelines of various surgical procedures, and should be instructed and trained systematically before performing the surgery.
3. Post-operative follow-up: A team of bariatric surgeons, internists and nutritionists familiar with this field is needed to follow up patients for life after surgery. Dietary guidance is a crucial part of ensuring the effectiveness of surgical treatment, avoiding long-term postoperative complications, and improving patients’ postoperative discomfort. The purpose is to form new dietary habits to promote and maintain improved glucose metabolism, while supplementing essential nutrients to avoid patient discomfort and reduce the risk of surgical side effects.